Method of making a propeller



Nov. 13, 1934. J. sQuIREs METHOD OF MAKING A PROPELLER Original Filed March 25, 1929 Patented Nov. 13, 1934 METHOD F MAKING A PROPELLER John Squires, Hagerstown, Md.

Application March 25, 1929, serial No. 349,696 Renewed May 18, 1932 9 Claims.

This invention relates to propeller blades and to methods of manufacturing the same, and has particular reference to the blades of air craft propellers.

An object of the invention is to provide a propeller blade formed from standard tubular stock, through subjecting the same to suitable forming operations.

Another object is to provide for gradually relO ducing the thickness of the walls of a hollow propeller blade from its inner to its outer end, so as to vary the strength of the blade at different points of its length, according to the stresses encountered at such points in use, and thus greatly l5 reduce the magnitude of centrifugal stresses arising in such use.

Still another object is to provide a method of transforming a length of tubular stock into a hollow propeller blade of airfoil section by,l a

26 series of drawing and forming operations.

These and Various other objects the invention attains by the construction hereinafter described and illustrated in the accompanying drawing, wherein:

Fig. 1 is a longitudinal sectional view of a length of tubular stock from which a propeller blade is to be formed,

Fig. 2 is a similar section, showingthe tapered form which the stock first assumes, and showing 30 the mandrel which gives it such form.

Fig. 3 shows the stock again in longitudinal section, being subjected to the next forming operation, through which its wall thickness is gradually varied from end to end.

Fig. 4 sectionally illustrates the blade in the next step of its formation,'and also the dies employed in such step.

Fig. 5 is a longitudinal sectional View of the completed blade.

Figs. 6 and 7 are relatively transverse elevational views of the blade completed, except for the fashioning of its inner end, to engage a hub member, Fig. 6 showing the blade partly in section.

Fig. 8 is a cross sectional view taken line 8-8 of Fig. 6.

Fig. 9 is a fragmentary view in side elevation and partial section of the inner end portion of a completed blade, showing one manner of adapting 50 it to engage a hub.

Fig. 10 is a similar view, showing a somewhat modified provision for retaining the blade engaged with a hub.

Referring now more in detail to the drawing,

55 the reference character 1 designates a length of on the (Cl. ,Z9-156.8)

metal tubing of conventional cylindrical formation with Walls of uniform thickness, and further designates the successive forms imparted to said tubing and the blades which it finally forms. Any metal having the necessary strength and ductility may be employed, a good grade of steel being preferred.

The first step in fashioning the tube 1 is to 1 ynally conforming to the minimum external diameter kof the tapered tube, is slipped over the reduced end of the tube and forced along the latter kto its other end, drawing the metal of the tube as indicated in Figure 3 and gradually reducing the thickness of the tube wall as the latter increases in internal diameter. It will, of course, be understood that the flow of metal thus produced by the die 4 effects an increase in the length of the tube. The mandrel 2 is now removed and a mandrel 3, of the same taper, is substituted in its place.

It will be noted that the inner end portion of the mandrel 3 is of cylindrical form and of a diameter reduced by the presence of a tapering shoulder 7 at the juncture of said portion with the main body of the mandrel. The next step in forming the blade consists in upsetting the inner end portion ofthe tube l as indicated at 8 by applying dies 9 to said end portion while heated and while the main body ofthe tube is embraced by dies 10.

Finally the outer end portion of the tube l is gradually drawn in by suitable die, trimming, or other operations, which will be obvious to those familiar with the art, and said end is closed by a welding operation in rounded form, appearing at 11 (Figures 5, 6 and 7) By further die operations the blade is then flattened so as to produce sharply divergent walls, forming a sharp angle at one edge of the propeller and gradually rounded at the other end thereof, as best appears in Figure 8, to effect the desired airfoil section to the blade.

To adapt the blade to be secured within a suitable socket carried by a propeller hub member (not shown), the thickened base portion 8 may be screw-threaded as indicated in Figure 5, or

may have rings machined thereon as appears in Figure 9, or retaining rings may be formed upon said portion by a rolling process, such rings being illustrated in Figure 10.

The described method of manufacturing propeller blades lends itself to rapid production and is productive of a very strong blade, which in use is subject to minimum centrifugal stresses owing to the distributionv of the metal in its walls as has been described. Furthermore, the tubular contruction of the completed blade is productive of' a maximum of strength with a of weight. y

While the described method is primarily intended to be employed in manufacturing propeller blades, it is to be understoodthat said method as above described and hereafter claimed is considered to cover the production of any articles to which it may be suited.

Formal changes may be made in the specific embodiment of the invention described without departing from the spirit or substance of the broad invention, the scope of which is commensurate with the appended claims.

What I claim is: j

1. The method of forming propeller blades, consisting in fashioning a length of tubular stock to a gradually varying diameter, then gradually decreasing the thickness of its wall from its lesser diameter to its larger diameter extremity by a die operation, then closing its larger diameter end and forming its other end with a supporting portion.

2. The method of `forming a propeller blade, consisting in first fashioning a piece of tubular stock to a gradually varying diameter of substantially equal wall thickness, then progressively flowing the metal in said'stock from end to end thereof to gradually reduce the thickness of its wall from its lesser diameter to its larger diameter extremity, then closing and rounding the larger diameter extremity and forming a securing portion upon the other extremity.

3. 'I 'he method of forming propeller blades, consisting in expanding a length of tubular stock to gradually vary its diameter from end to end, thendrawing out said stock at its larger diameter end while progressively decreasing the thickness of the wall of the stock toward said end from the lesser diameter end, and then closing the larger diameter end and forming a securing portion on the lesser diameter end.

4. In the manufacture of a propeller blade, the successive steps of gradually tapering a length of 1,9so,ss4 originally cylindrical tubular stock, and support ing one of the tapered faces of its wall against change in size, while progressively drawing the other to vary the thickness Vof said wall gradually from end to end of the. stock.

5. In the. manufacture of apropeller blader the successive steps of tapering a piece of originalthen progressively drawing.` the outer surface of said stock from its smaller to its larger diameter end while maintaining its interior surface against change in size to give it a uniform external diameter and a wall of gradually varying thickness.

6. The method of forming a-propeller blade consisting in forcing into a cylindrical metal member having a substantially uniform wall thickness a taperedmandrel whereby to change said member to a frusto-conical formation, then forcing said member through a ring die whereby to return its outer surface to cylindrical formation, closing the outer end of said member, and then deforming said member to/suitable blade shape.

7. The method of forming a propeller blade shape, supporting said member interiorly against reduction in size while passing it through a ring die to return its exterior surface to true cylin.-

drical formation, closing the outer end of said member, and then changing the cross-section of said 'member from circular form to a attened shape of airfoil section.

. 8. In the manufacture of a propeller blade from a cylindrical metal tube, the steps of acting upon said tube to vary both its internal and external diameters over at least a portion of the length thereof, interiorly supporting said tube against reduction in internal size and shape as thus varied, and forcing a die over said tube while so internally supported to produce a uniformity of exterior diameter therefor.

9. In the manufacture of a propeller blade from a cylindrical metal tube, the steps of acting upon said tube to taper both its internal and external diameters from one end toward the other thereof, interiorly supporting said tube against reduction in internal size and shape, as thus tapered, and forcing a die over said tube while so internally supported to produce a uniformity of exterior diameter therefor.

JOI-IN SQUIRES. 

